@stdlib/math-base-special-factorial
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    0.0.6 • Public • Published

    Factorial

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    Factorial function.

    The factorial function may be defined as the product

    Factorial function definition

    or according to the recurrence relation

    Factorial function recurrence relation

    Following the convention for an empty product, in all definitions,

    Zero factorial

    The Gamma function extends the factorial function for non-integer values.

    Factorial function extension via the Gamma function

    The factorial of a negative integer is not defined.

    Installation

    npm install @stdlib/math-base-special-factorial

    Usage

    var factorial = require( '@stdlib/math-base-special-factorial' );

    factorial( x )

    Evaluates the factorial function.

    var v = factorial( 3.0 );
    // returns 6.0
    
    v = factorial( -1.5 );
    // returns ~-3.545
    
    v = factorial( -0.5 );
    // returns ~1.772
    
    v = factorial( 0.5 );
    // returns ~0.886
    
    v = factorial( -10.0 );
    // returns NaN
    
    v = factorial( 171.0 );
    // returns Infinity
    
    v = factorial( NaN );
    // returns NaN

    Examples

    var incrspace = require( '@stdlib/array-base-incrspace' );
    var factorial = require( '@stdlib/math-base-special-factorial' );
    
    var x = incrspace( -10.0, 100.0, 1.0 );
    
    var i;
    for ( i = 0; i < x.length; i++ ) {
        console.log( 'x: %d, f(x): %d', x[ i ], factorial( x[ i ] ) );
    }

    See Also


    Notice

    This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

    For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.

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    License

    See LICENSE.

    Copyright

    Copyright © 2016-2022. The Stdlib Authors.

    Install

    npm i @stdlib/math-base-special-factorial

    Homepage

    stdlib.io

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